Manufacture of powdered milx



Patented 'l 'eb. 23, 1926.

UNITED STATES PATENT OFFICE. I

noimnannnax cnarsrsusnn, or wmnson, vrcronm, nosrnanm. manurac'ron'n or rownnnnn' mnx.

N'o Drawing. Application filed- April 23, 1925. Serial No. 25,435.

T'oaZZ whom it may concern: suitable. The desirable quantity of sodium Be it known that I, NORMAN HENRY oxalate to be added should, however, be the CHRISTENSEN, a subject of the King of Great minimum quantity which will produce the Britain, residing at Windsor, in the State of required result.

Victoria, Commonwealth of 'Australia, have The sodium oxalate decomposes portion c invented new and useful Improvements in of the calcium content of the milk and forms the Manufacture of Powdered Milk, of calcium oxalate which, being an insoluble which the following is a specification. compound, is immediately preci itated or This invention relates to improvements in thrown down. The treated mil is then the manufacture of powdered or dried milk passed through centrifugal separators or and similar milk products, and particularly cleaners, filters or like apparatus, wherein to that process of manufacture wherein the the precipitated calcium oxalate is removed. milk is desiccated by being passed in a. thin Small quantities of sodium citrate and film or layer over a heated roller or rollers. also sodium carbonate or other suitable This process of manufacture, although one alkali are then added to the treated milk. of the cheapest and most efficient processes The quantity of sodium citrate added may now in use, has the great disadvantage that vary up to six ounces per one thousand the milk powder produced is notwholly pounds of milk, while the quantity of sosoluble in water and is therefore entirely undium carbonate or alkali may vary up to suitable for many purposes. The cause of ten ounces per-'onethousand pounds of milk. this insolubility is that during the desicca- The milk' after being allowed to stand for tion of the milk by the heated rollers, the a short period is then desiccated in the casein principle in the milk is afi'ected by usual manner by being passed in a thin film the high temperature and becomes hardened or layer over a heated roller or rollers. To and insoluble.

The object of the present invention is to the treated milk, the milk may be first conprovide a process of treating milk prior to densed in vacuum boilers prior to being desiccation whereby the powdered milk passed over the heated rollers.

. product produced will be completely soluble 'If desired, the precipitated calcium oxain water. late need not necessarily be removed from The invention broadly consists in initially the milk, but it can be allowed to remain in treating the milk so as to remove or render the final dried product, as when the calcium chemically inert a portion of its calcium salts are in this state, they are chemically content. The improved process is based upinert and insoluble, and thus have no effect on the fact that, when a small portion of upon the casein while the milk is being the calcium content of the milk is removed desiccated. or rendered chemically inert in respect to In the carrying out of the improved procthe milk, the casein is then more easily acted ess, it is not necessary that all of the milk to upon by small quantities of added combe dried be treated with the sodium oxalate, pounds, such as sodium citrate and sodium but, for convenience, the milk can be divided carbonate or other alkali, and is thus eninto portions and the sodium oxalate added to abled to withstand the high temperature of only one of such portions. This portion after the heated rollers without being affected or filtering is then again returned tothe other becoming hardened and insoluble. 1 untreated portions and'is mixed therewith. In one preferred method of carrying the The treated portion of the milk should, invention into efiect, a small quantity of however, never be less than at least one third sodium oxalate is first added to the milk and of the total bulk of milk to be dried. the milk then stirred and allowed to stand 111 the treatment of full cream milk for for a period of about five minutes. The the production of whole milk powder, it is quantity of sodium oxalate added will vary preferable to divide the bulk of milk into according to the quality of the milk being portions in the manner previously described,

treated, the time of the year, and also the and to then add the sodium oxalate to only climatic conditions, but I have found that one of said portions. This ortion of the for an ordinary sample of milk, a quantity milk is then passed throng a separator of up to twelve ounces of sodium oxalate which removes the precipitated calclum per one thousand pounds of milk is very oxalate and separab the cream from the ensure rapid and thorough desiccation of milk. The separated cream is again re this method is unsuitable as the resultant parts of water dried product is rendered completely insoluble. lVith the present process, however, the fact that the milk is pre-condensed prior to desiccation and treatment does not in any way affect the solubility ofthe dried powder. For full cream milk, I find that a degree of concentration of twenty-three degrees Quevenne lactometer reading at sixty degrees Fahrenheit (when diluted to the ratio of one art of concentrate to three i gives highly satisfactory re,- sults with the improved process. For skim milk, however, it is desirable to concentrate the milk to thirty-three degrees Quevenne lactometer reading at sixty degrees Fah renheit (when diluted to the ratio of one part of concentrate to three parts of water). The above degrees of concentration must, however, be regarded merely as examples, as local conditions and also the quality of the milk have very much effect.

In the production of skim milk powder according to the improved process, it is found that the quality of the final product is greatly improved if the milk be skimmed to butter fat. In the treatment of one thousand pounds of skim milk, the following quantities have been found to be very satis factorysod1um oxalate ten ounces, SOdlum carbonate eight ouncessodium citrate six ounces.

These quantities can, however,'be varied as required, the desirable uantities being obtained by watching the co or of the product from the heated'rollers and also the color of the solution obtained bydissolving the dried powder in water. If the milk powder is very soluble and the color of the solution is too yellow. smaller quantities should be I used, the aim being to use as little as possible to bring about the desired result.

It is to. be understood that the invention is not limited solely to the use of sodium oxalate for the precipitation of the calcium content of the milk, but that other suitable oxalates may be used, or in fact any other salt which will form an insoluble and separable compound with the calcium content of the milk. Furthermore, it is also to be understood that the invention is not limited to t p ss at amo g the calc um cente s by precipitation as herein described, but that any other process may be employed which will result in its satisfactory removal. 1 The dried or powdered milk product obtained by the improved process is completely soluble in water at temperatures ranging from one hundred and five degrees Fahrenheit to boiling point, and when in solution it 7 forms a very satisfactory and wholesome substitute for fresh milk both for household and manufacturing pur oses. Furthermore, it is also very readlly digestible as facture of dried milk whichconsists in re- A moving a portion of the calcium content of the milk, prior to desiccation.

I 4. A process of treating milk in the manufacture of dried milk which consists in rendering a portion of the calcium content chemically inert relative to the milk prior to desiccation.

5. A process of treating milk in the manu- A facture of dried milk which consists in precifpltatmg a portion of the calcium content 0 the milk prior to desiccation.

6. A process of treating milk in the manufacture of dried milk which consists in precipitating a portion of the calcium content of the milk, and then treating the milk to remove the preci itated calcium.

7 A process of ing'a quantity of a soluble oxalate to the milk 7 treating milk in' the manu 'facture of dried milk which consists in addprior to desiccation to precipitate a portion of the calcium content.

8. A process of treating milk in the manufacture of dried milk which consists in adding a quantity of sodium oxalate to the milk prior to desiccationto precipitate. a portion of the calcium content;

9. A process of treating milk in the manufracture of dried milk which consists in addmg a quantity of sodium oxalate to the milk prior to desiccation to precipitate a portion of the calcium content, and then treating the milk to remove the precipitated calcium.

10. A process of treating milk,in the manufacture of dried milk which consists in adding a quantity of sodium oxalate to the milk prior to desiccation to precipitate a. portion of the calcium content, treating the mi t ass s th Precipitated l ium and then adding quantities of sodium citrate and sodium carbonate or alkali.

11. Amprocess of treating milk in the' manufacture of dried milk which conslsts in dividing the milk into portions, adding a quantity of sodium oxalate to one portion to precipitate a portion of the calcium content, treating that portion to remove the precipitated calcium and then returning the treated portion to the untreated portions.

12. A process of manufacturing dried milk which consists in first adding a quantity of sodium oxalate to milk to precipitate a portion of the calcium content, treating the milk to remove the precipitated calcium, adding quantities of sodium citrate and an alkali to the milk, and then desiccating the milk by passing it in a thin 'film or layer over a heated roller.

In testimony whereof I affix my signature.

NORMAN HENRY CHRISTENSEN.- 

